Technical Field
The present invention relates to solar power generation systems and failure diagnosis methods therefor, such as a failure diagnosis technology for a solar power generation system including a number of solar battery modules.
Background Art
In a large-scale solar power generation system such as represented by a large photovoltaic power plant, thousands to hundreds of thousands of 200 to 300 W-class solar battery modules are installed at a single generation site. The large-scale solar power generation system requires failure detection technology and maintenance technology. Outputs from the solar battery modules for the same solar radiation amount and temperature conditions gradually decrease due to aging degradation. However, some of the modules may lose their output rapidly due to manufacturing quality or physical damage. In the present specification, the state of a rapid decrease in output will be referred to as a “failure”.
In order to detect failure from the thousands to hundreds of thousands of 200 to 300 W-class solar battery modules, Patent Document 1 proposes a failure determination method whereby a measurement means and a communication means are provided for each solar battery module, and results transmitted from the communication means are compared with a threshold value. Patent Document 2 describes a method for determining failure by, due to measurement means cost restrictions, connecting measurement means in the unit of a “solar battery string” in which solar battery modules are connected in series. Further, Patent Document 3 describes a method whereby a string average current calculated from an overall average is compared with each string current, and a failure is recognized when there is a certain ratio of decrease in the string current. Thus, Patent Documents 1 to 3 describe a method whereby measurement means and communication means are provided on a solar battery module basis, and a method whereby measurement means and communication means are provided on a solar battery string basis.